The strict legal environmental protection rules necessitate the transition from disposable to reusable barrel units, such as, for example, barrels of plastic or steel. The changeover to barrel units having a larger volume with the objective of reducing the residual amounts, and the development of novel multiple-trip barrel units which can be reconditioned with a view toward ridding the environment of harmful substances and which can be optimally emptied of residue and can readily be cleaned for purposes of reconditioning as well as for a proper waste disposal by nonpolluting destruction, e.g. by combustion, or for reprocessing of the manufacturing material is desirable.
The development of reconditionable and easily disposable solid barrel units protected against contamination by deleterious substances, essentially barrels of plastic and steel, resulted in the lid-equipped barrels of this type and in lid-spigoted barrels known, for example, from DE 35 39 656 Al replacing, in part, the heretofore utilized sealed bunghole barrels. These barrels are equipped, as needed, with a flexible inside sheath denoted as inliner or, respectively, with a bag of a synthetic resin sheeting, e.g. a polyethylene sheet, or of a diffusion-proof, co-extruded metal-plastic composite sheet, for example an aluminum foil laminated on both sides with polyethylene. Barrels with an inliner are known, for example, from DE 88 10 760 U1. The inliners are used with plastic and steel barrels in case these are filled with products causing problems in their disposal, such as dispersions, e.g. paints, which can hardly be removed any more from the barrel wall after drying. Inliners of a diffusion-proof composite sheeting prevent in case of plastic barrels the diffusion of solvent-containing filling material into the barrel wall and a possible rediffusion of solvents from the barrel wall. In case of steel barrels, the inner liner saves the internal varnishing heretofore required for protecting the steel sheet against aggressive media and corrosion.